The overall objective of this project is to use lexical-phonological profiling to improve clinical diagnostics and prognostics for children between 2 1/2 - and 4-years with mild to moderate delays in speech sound acquisition. The first specific aim is to obtain normative data regarding the expected relationship between speech production ability and vocabulary ability from a large sample of 2- to 4-year-old children with and without speech sound disorder. The second specific aim is to determine to what extent the observed relationship between speech production ability and vocabulary ability is predictive of continued speech delay or normalized articulation. These aims will be achieved by using frequently used standardized tests to determine expressive and receptive vocabulary ability and articulation ability in a large, demographically representative sample of children between the ages of 2 1/2 and 4 years. This information will be used to establish normative data regarding the expected relationship between vocabulary and articulation ability. Follow-up assessment with children who score below normal limits on the articulation test will be conducted at 6 months and 1 year post initial evaluation to determine whether the observed phonological-lexical relationship is predictive of short-term speech sound normalization. Given the well-established connection between vocabulary and phonological ability in typical development, it is predicted that children with a large dissociation between vocabulary ability and speech production ability will be less likely to experience short-term speech sound normalization without intervention than children with more commensurate abilities in each area. Information obtained will assist clinicians in the decision making process for young children with mild to moderate delays in speech sound acquisition and will represent an innovative method for differential diagnosis of speech and language delays.